Simulation of the Hydrologic Effects of Afforestation in the Tacuarembó River Basin, Uruguay

Abstract

The Soil and Water Assessment Tool (SWAT) was used to simulate the hydrology of two small paired catchments in northern Uruguay. The control and treatment catchments (69 and 108 ha, respectively) were monitored for a three-year pretreatment period during which the land use was grassland with livestock grazing. Subsequently, the treatment catchment was planted (57% afforested) with loblolly pine (Pinus taeda). The objectives of the modeling study were to simulate the hydrologic response of the two catchments during the pretreatment period and predict the hydrologic effects of converting the native pasture to pine plantation. SWAT models of the two catchments were calibrated and validated using data measured during the pretreatment period. The model predicted outflows from the catchments reasonably well as compared to observed outflows during the years with above average rainfall (5% to −13% error). Model efficiency (E) for daily outflow volumes was greater than 0.71, indicating a good fit between simulated and observed results. A 33-year continuous simulation was performed on three land uses: grassland with livestock grazing, grassland without grazing, and pine treatment. The conversion of the catchments from the baseline pasture condition with grazing resulted in a predicted reduction in average annual water yield from the catchments of 15% for native grassland without grazing, and 23% for pine trees. A maximum predicted hydrologic effect was estimated by maximizing the model parameter that increases the ability of pine trees to withdraw water from the ground. For this condition, the model predicted a 30% reduction in mean annual water yield from the afforested catchment.

Hydrological simulation in a basin of typical tropical climate and soil using the SWAT model part I: Calibration and validation tests

“…5B) periods. This same difficulty was found by other authors, such as Viola et al (2009), Pereira et al (2014a), and von Stackelberg et al (2007, and is related to the representation of the spatial and temporal rainfall distribution. The rainfall distribution in SWAT is conducted by associating the sub-basin with the nearest streamflow gauging station closest to its centroid, and because the sub-basin has only five rainfall gauging stations upstream from the control section in Astolfo Dutra, the spatial representativeness of some rainfall was compromised.…”

“…The years of 1994 and 1995 were used to warm up the model in order to eliminate the uncertainties existing in the beginning of modeling, particularly regarding the soil's water content (Viola et al, 2009;von Stackelberg et al, 2007;Zhang et al, 2007). The calibration was made for the average daily streamflow and was performed by trial and error by changing one parameter at a time and then analyzing the results.…”

“…SWAT has been widely used worldwide (Gassman et al, 2007) in hydrologic simulations of basins with different climates, topography, geology, pedology, and vegetation conditions and with different drainage areas (Andrade et al, 2013a;Durães et al, 2011;Pereira et al, 2014a,b;von Stackelberg et al, 2007), yielding satisfactory results (performance) most of the time. However, for the SWAT to be broadly disseminated worldwide, it still requires studies in basins with climate and soil typical of tropical conditions and in highly irregular terrain, such as the Pomba River Basin in southeastern Brazil.…”

Land use change in a 200‐year period and its effect on blue and green water flow in two Slovenian Mediterranean catchments—lessons for the future

“…Especially in the case of the changed (increase/decrease) intensity of land cultivation like abandonment, reclamation, urban development and forest density (Heuvelmans et al, 2004;Schuol et al, 2008;Huang et al, 2009;Maes et al, 2009;Pisinaras et al, 2010;Bielsa et al, 2011;Dirmeyer, 2011). Different studies found strong statistical relationships between the hydrological conditions and land use change, which affects also the ecosystems (Klocking and Haberlandt, 2002;Von Stackelberg et al, 2007) and physicochemical soil properties and especially the hydraulic characteristics and processes (soil water retention capacity and surface runoff) (Eckhardt et al, 2003;Bormann et al, 2007). The results of this study also confirm the influence of a changed share of the forests in the area on the GWF (AET) (Klocking and Haberlandt, 2002;Pisinaras et al, 2010).…”

Contribution a L'étude électrochimique de dérivés de L'acide mercapto‐2 pyridine carboxylique‐5

“…Les mesures coulometriques confirment le nombre d'electrons echanges at permettent la mise en evidence du thiomethanol produit dans la reaction. D'autre part, pour expliquer le comportement de la vague en fonction du pH, on p u t suggerer un mecanisme analogue I celui propose par M. Von Stackelberg(13) pour elucider la reduction de derives halogenes : la reaction s'effectuerait en deux Btapes, dont la premiere est lente, determine la cinetique de la reac-tion et n'inclut pas l'intervention de protons.Les variations de potentiel observees lorsque le pH de la solution varie, doivent etre attribuees a l'intense adSOrDtiOn du depolarisant et surtout des produits de reduction a la surface meme de l'electrode a goutte de mercure.L'adsorption de ces substances sur l'electrode a Bte mise en evidence anterieurement tant en polarographie conventionnelle qu'alternative ainsi qu'en voltammetrie cyclique(14).La hauteur de la premiere vague varie proportionnellement a la hauteur d e la colonne de mercure presentant ainsi un caractere se rapprochant des prevagues decrites dans les travaux de Brdicka (15,,b). En polarographie alternative (AC), le pic qui lui correspond varie peu en fonction de la f r h u e n c e mais l'epaulement resultant de l'adsorption, tres sensible aux variations de frequence, n'apparalt qu'entre 45 et 270 Hz.…”